1. Field of the Invention
The present invention relates to an image processing apparatus applicable to a computer system and a method of the same, and more specifically to an image processing apparatus and a method of superimposing a second video image over at least part of a first video image.
2. Description of the Related Art
A known technique for superimposing a second video image on a first video image on a display is typically disclosed in description and FIG. 2 of JAPANESE PATENT LAYING-OPEN GAZETTE No. 2-298176 by the applicant of the present invention.
FIG. 18 shows a conventional method of superimposing a video image over another on a monitor of a personal computer with the known technique. A first video image, including letter images such as "A" and "B", generated by the personal computer is masked in a rectangular superimposed area SIA while a second video image, including a vehicle image, given by a video unit is displayed in the superimposed area SIA.
In the example of FIG. 18, a background image area in the second video image other than a vehicle image is sometimes not required and is to be favorably replaced by the video image generated by the personal computer. In the conventional technique, however, a superimposed area of a predetermined shape is previously set, and it is thereby impossible to superimpose only the vehicle image portion. This causes a non-required background image to exist around the required vehicle image in the superimposed area SIA, and reduces an area of the screen to display the video image generated by the personal computer accordingly. Similar problems arise in a variety of video devices such as presentation tools and game machines as well as personal computers.